Fault location detection and distance protection apparatus and associated method

An apparatus for determining a fault location distance or a distance for distance protection in a multi-phase power transmission medium, the apparatus configured to;

• determine a set of line fault parameters up, iPR, iPX and iP0 based on a measurement sample of voltage and current values at a measurement point for phases of a multi-phase current of said power transmission medium and a fault type, the set of line fault parameters determined at a plurality of sample times, n;
• determine a derivative with respect to time of one of the line fault parameters iPX representative of an inductive part of measured faulty phase current;
• determine a set of phasors {dot over (U)}P(n), İPR(n), İPX(n), and İP0(n), using a Fourier transformation of the derivative and of the remaining line fault parameters at the plurality of sample times and use said set of phasors to determine a fault location distance or distance projection distance along the power transmission medium;
• wherein, the determination of the fault location distance or the distance protection distance is based on the line equation;
• U
• .
• P
• =
• U
• .
• F
• +
• [
• R
• 1
• ⁢
• I
• .
• PR
• +
• X
• 1
• ω
• 0
• ⁢
• I
• .
• PX
• ]
• ⁢
• D
• F
• where {dot over (U)}P, İPR, and İPX comprise the Fourier transforms of the line fault parameters up, IPR and the derivative iPX, {dot over (U)}F is a Fourier transform of the voltage at the fault location, R1 is a positive sequence resistance of the power transmission medium per length (ohm/km), DF is the fault location distance, X1 is a positive sequence reactance of the power transmission medium per length (ohm/km) and ω0 is the fundamental angular frequency where ω0=2πf0 and f0 is the fundamental frequency of the current of the power transmission medium;
• and
• clearing a fault by tripping a breaker adjacent to a protective zone determined based at least in part on the determination of the fault location distance or the distance protection distance.